Which process uses grinding and shredding in wastewater treatment?

The correct answer is the process known as the comminutor, which is specifically designed to grind and shred large solids present in wastewater. This process is crucial because it reduces the size of these solids to prevent damage to pumps and other equipment in the treatment system. By grinding and shredding materials, the comminutor helps to facilitate smoother flow through the wastewater treatment facilities, allowing for more efficient treatment processes downstream.

In contrast, screening refers to the initial phase of wastewater treatment where larger debris and materials are physically removed from the flow using screens or grates, but it does not involve grinding or shredding. Pre-aeration focuses on increasing dissolved oxygen levels in wastewater to promote the growth of aerobic microorganisms, but it does not address solid waste size reduction. Grit removal is aimed at eliminating heavier inorganic particles, such as sand and gravel, from wastewater; however, this process does not involve the grinding and shredding of organic solids. Each of these processes plays a vital role in wastewater treatment, but the comminutor specifically addresses the need to prepare solids for further treatment by reducing their size effectively.